Midwestern Alfalfa Responds To Mild Weather

The growing season for alfalfa is off to an extremely fast start in most of the Upper Midwest. Yet growers are concerned about possible frost damage.

“We broke dormancy early, that’s for sure,” reports Phil Kaatz, Michigan State University Extension forage educator, of the warm March weather’s effect on alfalfa. As of April 1, many parts of the state had already accumulated 250-300 growing degree days (base 41 degrees).

A late-March cold snap sent overnight lows below freezing in most parts of lower Michigan and the Upper Peninsula. “It alarmed some producers. But overall, I don’t think it will lead to any widespread problems. Generally, temperatures lower than what was experienced are required to kill alfalfa stems. The stems are usually what get damaged.”

Many Michigan producers may be in for an early alfalfa harvest, Kaatz says. “Normally in the southern part of the state, first cutting for alfalfa is around May 25. If the crop is ready five to seven days early, it could create some scheduling problems for producers who are trying to wrap up corn or soybean planting at the same time.”

In central Minnesota, warm weather through much of March has the alfalfa two to three weeks ahead of where it would normally be. So says Dan Martens, University of Minnesota Extension educator in Stearns, Morrison and Benton counties. “Things are greening up nicely. We have some alfalfa with 2-3” of growth,” he reports.

A few trouble spots exist. “We had a dry fall in some areas that may have limited the ability of alfalfa to put down good root reserves. We also had a couple of cold days this winter when there may not have been a lot of snow cover for the alfalfa. Overall, though, most reports we’ve been hearing make us optimistic that alfalfa came through the winter in pretty good shape.”

The weather will determine what happens going forward. “It turned a little cool and cloudy in the last week of March, and that probably slowed growth a little. But the crop is up and going, and whatever warm weather we get from this point on will keep it moving along.”

Alfalfa is also growing nicely in Iowa, says Steve Barnhart, Extension forage specialist with Iowa State University. “I haven’t heard of any significant problems with winterkill or winter injury,” he says. “The regrowth has been pretty good in most areas.”

Spring black stem has been “firing up in some fields.” The fungal disease can occur in any growing season, depending on temperature and humidity.

If favorable weather continues, many Iowa growers could also be in for an early harvest. “That’s going to be less of a concern for silage makers, including those making baled silage, than for dry hay makers who require an extended drying period,” says Barnhart.

In Indiana, alfalfa fields look more like they normally do in late April or early May, according to Purdue University Extension forage specialist Keith Johnson. “It’s an outlier year in terms of where we’re at for growth. We are weeks, not days, ahead of schedule.”

Johnson has been fielding questions from producers about cutting alfalfa now, mostly due to concerns about earlier-than-normal alfalfa weevil activity. “Harvesting early is seen as a way to stop the weevils without having to invest in an insecticide.”

While that can be a good strategy in some cases, he warns that there can also be a downside. “If you do take a first cutting too early, it could impact stand persistence. At some point in the season, you’ll need to delay a subsequent cutting and give the plants a chance to rest and rebuild carbohydrates.”

Dry weather could become a concern for Indiana growers, says Johnson. “We had abundant moisture through the winter. But now a lot of soil profiles are dry for this time of year. The crop is growing well to this date, but it would sure be nice to get a couple of showers in the next couple of weeks.”

For information on what to watch for if warm Midwestern weather turns wintery, read the advice from University of Wisconsin Extension forage specialist Dan Undersander in the story, "Managing Alfalfa After Frost."